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Atmospheric modelling for NOMAD-UVIS on board the ExoMars Trace Gas Orbiter mission
The Ultraviolet and Visible Spectrometer (UVIS) instrument development process requires the construction of an atmospheric model to provide synthetic UV transmission spectra. We discuss the requirements of the model to enable observational limits to be found, and the potential for certain atmospheric parameters to be further constrained
The Restriction Principle and Commuting Families of Toeplitz Operators on the Unit Ball
On the unit ball B^n we consider the weighted Bergman spaces H_\lambda and
their Toeplitz operators with bounded symbols. It is known from our previous
work that if a closed subgroup H of \widetilde{\SU(n,1)} has a
multiplicity-free restriction for the holomorphic discrete series of
\widetilde{\SU(n,1)}, then the family of Toeplitz operators with H-invariant
symbols pairwise commute. In this work we consider the case of maximal abelian
subgroups of \widetilde{\SU(n,1)} and provide a detailed proof of the pairwise
commutativity of the corresponding Toeplitz operators. To achieve this we
explicitly develop the restriction principle for each (conjugacy class of)
maximal abelian subgroup and obtain the corresponding Segal-Bargmann transform.
In particular, we obtain a multiplicity one result for the restriction of the
holomorphic discrete series to all maximal abelian subgroups. We also observe
that the Segal-Bargman transform is (up to a unitary transformation) a
convolution operator against a function that we write down explicitly for each
case. This can be used to obtain the explicit simultaneous diagonalization of
Toeplitz operators whose symbols are invariant by one of these maximal abelian
subgroups
Chiral-logarithmic Corrections to the S and T Parameters in Higgsless Models
Recently, Higgsless models have proven to be viable alternatives to the
Standard Model (SM) and supersymmetric models in describing the breaking of the
electroweak symmetry. Whether extra-dimensional in nature or their
deconstructed counterparts, the physical spectrum of these models typically
consists of ``towers'' of massive vector gauge bosons which carry the same
quantum numbers as the SM W and Z. In this paper, we calculate the one-loop,
chiral-logarithmic corrections to the S and T parameters from the lightest
(i.e. SM) and the next-to-lightest gauge bosons using a novel application of
the Pinch Technique. We perform our calculation using generic Feynman rules
with generic couplings such that our results can be applied to various models.
To demonstrate how to use our results, we calculate the leading
chiral-logarithmic corrections to the S and T parameters in the deconstructed
three site Higgsless model. As we point out, however, our results are not
exclusive to Higgsless models and may, in fact, be used to calculate the
one-loop corrections from additional gauge bosons in models with fundamental
(or composite) Higgs bosons.Comment: 45 pages, 15 figures, added references, analysis of three site model
expanded to include delocalized fermion
A Complete Atlas of HI Absorption toward HII Regions in the Southern Galactic Plane Survey (SGPS1)
We present a complete catalog of H I emission and absorption spectrum pairs,
toward H II regions, detectable within the boundaries of the Southern Galactic
Plane Survey (SGPS I), a total of 252 regions. The catalog is presented in
graphical, numerical and summary formats. We demonstrate an application of this
new dataset through an investigation of the locus of the Near 3kpc Arm.Comment: Accepted for publication by ApJS Feb 6, 2014. Data files and Figure
Set (252 images) to appear in the on-line version of the journa
Peripheral visual response time to colored stimuli imaged on the horizontal meridian
Two male observers were administered a binocular visual response time task to small (45 min arc), flashed, photopic stimuli at four dominant wavelengths (632 nm red; 583 nm yellow; 526 nm green; 464 nm blue) imaged across the horizontal retinal meridian. The stimuli were imaged at 10 deg arc intervals from 80 deg left to 90 deg right of fixation. Testing followed either prior light adaptation or prior dark adaptation. Results indicated that mean response time (RT) varies with stimulus color. RT is faster to yellow than to blue and green and slowest to red. In general, mean RT was found to increase from fovea to periphery for all four colors, with the curve for red stimuli exhibiting the most rapid positive acceleration with increasing angular eccentricity from the fovea. The shape of the RT distribution across the retina was also found to depend upon the state of light or dark adaptation. The findings are related to previous RT research and are discussed in terms of optimizing the color and position of colored displays on instrument panels
Small Engine Component Technology (SECT)
A study of small gas turbine engines was conducted to identify high payoff technologies for year-2000 engines and to define companion technology plans. The study addressed engines in the 186 to 746 KW (250 to 1000 shp) or equivalent thrust range for rotorcraft, commuter (turboprop), cruise missile (turbojet), and APU applications. The results show that aggressive advancement of high payoff technologies can produce significant benefits, including reduced SFC, weight, and cost for year-2000 engines. Mission studies for these engines show potential fuel burn reductions of 22 to 71 percent. These engine benefits translate into reductions in rotorcraft and commuter aircraft direct operating costs (DOC) of 7 to 11 percent, and in APU-related DOCs of 37 to 47 percent. The study further shows that cruise missile range can be increased by as much as 200 percent (320 percent with slurry fuels) for a year-2000 missile-turbojet system compared to a current rocket-powered system. The high payoff technologies were identified and the benefits quantified. Based on this, technology plans were defined for each of the four engine applications as recommended guidelines for further NASA research and technology efforts to establish technological readiness for the year 2000
An early warning indicator for atmospheric blocking events using transfer operators
The existence of persistent midlatitude atmospheric flow regimes with
time-scales larger than 5-10 days and indications of preferred transitions
between them motivates to develop early warning indicators for such regime
transitions. In this paper, we use a hemispheric barotropic model together with
estimates of transfer operators on a reduced phase space to develop an early
warning indicator of the zonal to blocked flow transition in this model. It is
shown that, the spectrum of the transfer operators can be used to study the
slow dynamics of the flow as well as the non-Markovian character of the
reduction. The slowest motions are thereby found to have time scales of three
to six weeks and to be associated with meta-stable regimes (and their
transitions) which can be detected as almost-invariant sets of the transfer
operator. From the energy budget of the model, we are able to explain the
meta-stability of the regimes and the existence of preferred transition paths.
Even though the model is highly simplified, the skill of the early warning
indicator is promising, suggesting that the transfer operator approach can be
used in parallel to an operational deterministic model for stochastic
prediction or to assess forecast uncertainty
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